Watch the STS-127 Mission Liftoff Live Is the Third Time the Charm???

Image Courtesy NASA

LAUNCH SCRUBBED AGAIN.
CHECK BACK LATERLAUNCH WINDOW OPENS AT 18.46 HOURS EASTERN TIME.

STS-127 (ISS assembly flight 2J/A) is the next space shuttle mission to the International Space Station (ISS).^[1] It will be the 23rd flight of Space Shuttle Endeavour. The primary purpose of the STS-127 mission is to deliver and install the final two components of the Japanese Experiment Module: the Exposed Facility (JEM EF), and the Exposed Section of the Experiment Logistics Module (ELM-ES).^[3][4]

When Endeavour docks with ISS, it will be the first time thirteen people have been at the station at the same time.^[5] It will also set a record for the most humans in space at the same time in the same vehicle—the space station. It will tie the record of thirteen people in space at any one time.

The first launch attempt on June 13, 2009, was scrubbed due to a gaseous hydrogen leak observed during tanking.^[6][7] The Ground Umbilical Carrier Plate on the external fuel tank experienced a potentially hazardous hydrogen gas leak similar to the fault that delayed the Space Shuttle Discovery, mission STS-119 in March 2009. Since a launch date of June 18 would have conflicted with the launch of the Lunar Reconnaissance Orbiter (LRO)/Lunar Crater Observation and Sensing Satellite (LCROSS), NASA managers discussed the conflict issues with both the Lunar Reconnaissance Orbiter project, as well as the Air Force Eastern Range that provides tracking support for rockets launched from Florida, and looked at options for launching the shuttle, without affecting the LRO project significantly.^[8][9] A decision was made to allow the shuttle to attempt a second launch on June 17, and LRO would launch on June 18.^[7]

The second launch attempt on June 17 was also scrubbed due to hydrogen leak issues seen from the GUCP.^[10] Due to conflicts with the launch of the LRO, and with a solar heating in spaceconstraint, the next available launch opportunity was scheduled for July 11.^[11][12] A successful tanking test for leak checks performed on July 1 with modified GUCP seals allowed launch to proceed for July 11 at 7:39 pm EDT.^[13] Due to lightning strikes near the launch pad during the evening of July 10, NASA scrubbed the launch for the third time and rescheduled for July 12 at 7:13 pm EDT.^[14]

Source: Wikipedia